Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish that this is a non-destructive, closed-world write. The description adds genuinely non-obvious behavioral facts the annotations lack: no model calls are made and no automatic approval step occurs, plus the data is clearly labeled as fictional. It stops short of saying what state is created or whether resuming mutates an existing sample.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.